Matthew,
We have be putting ground plane copper under MQFP-144 and other SMD ICs for
years with no apparent assembly problems or defects.  One again, proper
oven profiling is important here.  Also helps control EMI
emission/susceptability for the internal layers (if needed), has only a
small effect if board is designed properly.
Looking forward to 6 and 8 layers?
Roger M. Stoops, C.I.D., PCB Designer


Trimble
Engineering and Construction Division
5475 Kellenburger Rd.
Dayton, OH 45424-1099 USA
Ph: +01 937.233.8921 or +01 937.233.4574 ext 288
Fax: +01 937.233.7511






                    Matthew Lamkin
                    <matthew.lamkin@PROTEC-FIRE-DETECTI        To:     [log in to unmask]
                    ON.PLC.UK>                                 cc:
                    Sent by: DesignerCouncil                   Subject:     [DC] And another thing?
                    <[log in to unmask]>


                    06/14/01 09:01 AM
                    Please respond to "DesignerCouncil
                    E-Mail Forum."; Please respond to
                    Matthew Lamkin





Hello Again,

Should I (if there is room) place any groundplane (tied to 0v below)
underneath a MQFP208 chip, on the top copper/SMT side?

Or would this absorb some of the heat when it is being heated, and
consequently cause it to have poor solder connections?
(amongst all the other reasons for there being poor soldered joints ;-))

Matthew Lamkin.

---------------------------------------------------------------------------------

DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
---------------------------------------------------------------------------------

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------